Intratracheal pulmonary ventilation (ITPV) enhances the clearance of CO2 from dead space and lungs by a bias flow of gas administered in the distal trachea. ITPV flow is continuously administered through a separate catheter placed within an endotracheal tube (ETT). After exiting from catheter's tip in the distal trachea, the ...

The response of respiratory motor output to CO2 in the hypocapnic range (< 36 Torr PCO2) in the absence of hypoxemia is not well characterized in awake normal humans. We induced hypocapnia with hyperoxia in 16 normal volunteers by placing them on a volume-cycled ventilator in the assist mode. Subjects ...

BACKGROUND: The intravascular gas exchanger is a lung assist device for augmentation of gas exchange in critically ill patients with severe acute respiratory failure. These patients often require inotropic support therapy due to the cardiovascular instability that almost inevitably accompanies severe respiratory failure. METHODS: We investigated the interaction of vasoactive ...

The metabolism of gas gland cells of the swimbladder epithelium is specialized for the production of acidic metabolites that are released into the blood stream and provoke an increase in gas partial pressure by reducing the effective gas-carrying capacity of the blood. In a subsequent step this initial increase in ...

Pneumothorax can develop during laparoscopy, particularly during laparoscopic fundoplication, since the left parietal pleura is exposed and can be torn during dissection in the diaphragmatic hiatus. Such an event will result in specific pathophysiologic changes, since CO2, under pressure in the abdominal cavity, will pass into the pleural space. The ...

Bowie J R JR Department of Anesthesiology, University of South Florida College of Medicine, Tampa 33612, - - 1995

Our objective was to determine if rebreathing would reduce the gradient between arterial and end-tidal CO2 tension during positive-pressure ventilation. Experimental investigation. Anesthesiology laboratory. A total of 10 dogs of either sex. Anesthesia (sodium pentobarbital) and muscle relaxation (pancuronium) were induced and animals were tracheally intubated and ventilated with a ...

The effects of pneumoperitoneum with carbon dioxide and helium on systemic hemodynamics and arterial blood gases were investigated in pigs in an attempt to clarify the mechanisms by which pneumoperitoneum may induce organ dysfunction. A total of 16 anesthetized female pigs underwent pneumoperitoneum with carbon dioxide or helium (n = ...

Carbon dioxide pneumoperitoneum has been shown to produce respiratory and hemodynamic changes due to both CO2 absorption and the effects of increased intraperitoneal pressure. We have measured the blood gas, end-tidal CO2, and hemodynamic changes produced during extraperitoneal CO2 insufflation (n = 22). These have been compared with the changes ...

Clinical measures of ventilation and the relationship between arterial and end-tidal carbon dioxide tensions were studied during inhalational anaesthesia in 18 patients using a laryngeal mask airway or a facemask. Tidal volumes were similar in both groups but expired minute volume, respiratory rate and physiological deadspace ventilation were significantly increased ...

PETCO2 is often used as an estimate of PaCO2, with the understanding that PaCO2 usually exceeds PETCO2. During intraoperative craniotomies, because hyperventilation is used to therapeutically lower intracranial pressure, the difference between PaCO2 and PETCO2 (P(a-ET)CO2) has therapeutic implications. The P(a-ET)CO2 was hypothesized to be stable during craniotomies with relatively ...

We measured resting pulmonary gas exchange in eight subjects exposed to 9 or 14 days of microgravity (microG) during two Spacelab flights. Compared with preflight standing measurements, microG resulted in a significant reduction in tidal volume (15%) but an increase in respiratory frequency (9%). The increased frequency was caused chiefly ...

Controversy has been raised about the effects of systemic carbon dioxide accumulation versus the intra-abdominal pressure on hemodynamics during laparoscopy. We compared the acid-base and hemodynamic changes during pneumoperitoneum in a randomized cross-over study between CO2 and nitrogen gases to test the hypothesis that the CO2 absorbed during laparoscopy, rather ...

BACKGROUND: In the treatment of patients with life-threatening ventricular arrhythmia, transvenous implantable cardioverter/defibrillators provide significant advantages over devices requiring a thoracotomy. This study tested the hypothesis that a new carbon-fiber electrode, designed at the Technische Universität in Munich, Germany, has a lower defibrillation threshold (DFT) than standard transvenous defibrillation electrodes. ...

PURPOSE: Tracheal gas insufflation (TGI) improves the efficiency of conventional mechanical ventilation (CMV) by reducing the series dead space of the airways. Consequently, application of TGI as an adjunct to CMV may permit reducing tidal volume (VT) while limiting CO2 retention. We tested the extent to which panexpiratory TGI allows ...

Vasomotor effects of skin exposure to carbon dioxide (CO2) have been described in normal subjects. It was of interest, therefore, to determine whether percutaneous CO2 is of therapeutic benefit. In a randomized, double-blind study, 10 patients with lower limb arteriopathy (stage II) were investigated before and after local exposure for ...

BACKGROUND: Patients who are undergoing laparoscopic procedures can present with a number of ventilatory and circulatory problems. The use of a gasless technique for performing a laparoscopy by using a mechanical lifting device may potentially avoid such problems. OBJECTIVE: To compare the cardiorespiratory effects of laparoscopy with and without gas ...

The purpose of this study was to develop a technique to measure the oxygen cost of ventilation and the values of ventilatory parameters in seven normal horses rebreathing carbon dioxide (CO2). All the horses responded to increased inspiratory levels of CO2 by increasing their tidal volume (VT) and frequency of ...

The influences of laparoscopic techniques on respiratory function are reviewed according to the published literature. The influences are aroused by the applied pressure and the diffusion and absorption of the gas used. The published incidents of the technique are commented and the necessity of meticulous monitoring of the applied pressure ...

Carbon dioxide is the most commonly used gas for abdominal insufflation in laparoscopy today. Due to the solubility of carbon dioxide large volumes are absorbed into the circulation causing a high PCO2 and a low pH (respiratory acidosis). Carbon dioxide is also stored in several sites in the body and ...

The use of carbon dioxide to create a cavity for the operation of laparoscopic cholecystectomy leads to serious complications of the cardiovascular system; consequently, patients with ischaemic heart disease can be put at greater risk. For example, on reaching an intra-abdominal pressure of 15mmHg, a fall of about 35% of ...

Reliable recordings of carbon dioxide concentrations during spontaneous respiration can be obtained from a catheter positioned in the hypopharynx. The present study investigated the possible influence on end-tidal carbon dioxide measurement of nasal oxygen administration, position of the sampling catheter and mouth breathing. The study demonstrated that not only can ...

OBJECTIVE: To estimate the rate of exchange of selected gases across the middle ear (ME) mucosa and define the exchange limitations. DESIGN: At separate sessions, the ME was inflated via the eustachian tube with a bolus of pure nitrogen, carbon dioxide, oxygen, or nitrous oxide, and ME pressures were recorded ...

New mathematical algorithms have been applied to a computer controlled closed breathing circuit system for non-invasive measurement of cardiac output (COniv). This system has been described in an animal study. Forty patients were studied 5 and 18 hours after cardiac surgery using the thermodilution technique as the reference (COtd). The ...

Control of physiological parameters such as respiration, blood pressure, and arterial blood gases has been difficult in the mouse due to the lack of technology required to monitor these parameters in small animals. Here we report that anesthetized and artificially ventilated mice can be maintained under physiological control for several ...

Laparoscopic surgery with CO2 insufflation is associated with adverse effects on hemodynamics and gas exchange. The abdominal wall retractor (AWR) is an alternative for pneumoperitoneum. Hemodynamics and gas exchange during the use of an AWR were compared to those of CO2 pneumoperitoneum. In eight pigs subjected to 1 h of ...

Regions within the rostral ventral medullary surface (RVMS) play an important role in cardiorespiratory responses to CO2 during anesthesia. Activity within a RVMS area, in which local cooling elicited marked ventilatory and blood pressure reductions, was measured as 660 nm scattered light changes in 5 goats following 5% CO2 challenges ...

OBJECTIVES: We evaluated the efficacy of a new laparoscopic dissecting instrument that fires intermittent bursts of high-pressure carbon dioxide to separate tissue along natural planes. METHODS: The pneumodissector (PD) was used in 2 patients undergoing laparoscopic procedures. Serum creatinine and bicarbonate were measured before and after the procedure, and arterial ...

We evaluated the ventilatory effects and blood gas changes of prolonged CO2-pneumoperitoneum in nor-moventilated patients and examined the respiratory and gas exchange consequences of head-down positioning (25-30 degrees) and CO2 insufflation into the peritoneal cavity in 20 patients without major cardiorespiratory disorders in various phases of laparoscopic hysterectomy. The patients ...

Twenty patients having laparoscopic cholecystectomies were studied for changes in thoracic and lung compliance at 5, 10 and 15 mmHg of intra-abdominal pressure. Fifteen mmHg of intra-abdominal pressure decreased the thoracic and the lung static compliance by 49 and 39% respectively. This was unaffected by the degree of head elevation. ...

OBJECTIVE: The purpose of this study was to determine the optimal parenteral feeding regimen for infants with compromised respiratory function. METHODS: We studied the influence of varying the source of energy on respiratory gas exchange in 10 infants who were supported by mechanical ventilation and who received intravenous feedings. Two ...

An accepted method of tracheal reintubation is to pass an endotracheal tube (ETT) over a jet stylet (JS). It is desirable to confirm tracheal reintubation prior to removing the JS from its known intratracheal location. The purpose of this study was to determine the functional size equivalent of the annular ...

In some patients obstructive sleep apnoea (OSA) may co-exist with chronic obstructive pulmonary disease (COPD) and respiratory failure; the so-called "overlap syndrome". Obstructive, hypercapnic patients have both blunted ventilatory and mouth occlusion pressure responses during CO2 stimulation. The purpose of this study was to compare the pattern of breathing and ...

In two patients, operated on because of gastroesophageal reflux, carbon dioxide pneumothorax developed during laparoscopic Nissen fundoplication. In both instances, decrease of lung compliance and a change of pressure-volume loop configuration, computed and illustrated with on-line spirometry, led quickly to diagnosis of this complication. We conclude that continuous spirometry is ...

Laparoscopic surgery generally is regarded as a safe procedure when a preset pressure is used in the carbon dioxide insufflator. However, a fixed pressure setting is not appropriate when insufflating a very large or a very small abdomen. Presently, extrapolation from the commonly used 15 mm Hg to an appropriate ...

OBJECTIVE: The purpose of this study was to evaluate the reliability and accuracy of a new continuous intra-arterial blood gas monitoring system (IABG; PB3300, Puritan Bennett) over a prolonged period of time (> 7 days). DESIGN: Prospective criterion standard study. SETTING: Anesthesiological intensive care unit in a university hospital. PATIENTS: ...

BACKGROUND: Hyperventilation is a frequently used method for inducing hypercarbia in neurosurgical patients. This practice requires careful carbon dioxide monitoring that might be replaced by a less expensive and less invasive alternative to arterial blood gas monitoring. OBJECTIVE: To determine the accuracy of end-tidal carbon dioxide monitoring in hyperventilated neurosurgical ...

Transthoracic endoscopic sympathectomy (TES) is an accepted standard surgical treatment for palmar hyperhidrosis. For anesthetic management, a double lumen endobronchial tube is usually used to deflate the lung on the operative side. Recently we have applied continuous insufflation of carbon dioxide (CO2) into the pleural cavity to merely compress one ...

When a gas mixture containing carbon dioxide (CO2) is inhaled by an individual, alveolar ventilation is increased. This ventilatory response to CO2 highlights the relationship between the increase in exercise ventilation and the increase in alveolar CO2 pressure (paCO2). This response is mediated centrally by brainstem chemoreceptors in the medulla ...

The physiological effect of CO2 pneumoperitoneum during laparoscopy is a great concern of the anesthesiologists. Its effect in pediatric laparoscopy has not been previously reported. The purpose of this study was to examine the physiological alteration of pediatric patients during CO2 pneumoperitoneum. One hundred and twenty six children aged from ...

Recent studies suggest that significant physiologic derangements can occur during laparoscopic surgery. Eighteen patients admitted for laparoscopic cholecystectomy were studied. The mean age was 46.7 (range 19-78). A standard anesthetic technique, reverse Trendelenburg positioning, and an abdominal insufflation pressure of 15 mmHg with CO2 were used with all subjects. Central ...

In gas exchange studies addressing the storage and transport of CO2 in dogs, a model in which cardiac output (QT) can be precisely controlled and measured would be beneficial. We identified problems with described extracorporeal circuits and implemented right atrial bypass (RAB) in dogs. In 6 anesthetized (chloralose and urethane), ...

Although pneumoperitoneum has been well tolerated in a predominantly healthy population, there is concern that an increased intraperitoneal pressure may be poorly tolerated in patients with marginal cardiopulmonary function. The purpose of this study was to demonstrate noninvasively the hemodynamic effects of carbon dioxide pneumoperitoneum utilizing biplane transesophageal echocardiography. Fourteen ...

Pneumoperitoneum with CO2 is associated with adverse effects, such as hypercarbia, arrhythmias, and circulatory depression, which may limit its use in patients with underlying disease. Some of these effects may be caused by CO2 absorption resulting in acid-base disturbances. Laparoscopic insufflation with helium may be a good alternative for CO2, ...

The authors prospectively examined the cardiorespiratory changes during brief laparoscopy (less than 15 minutes) in children. Intraoperative ventilatory management included a tidal volume of 12 mL/kg, with the rate adjusted to achieve an end-tidal CO2 (PETCO2) of 30 to 35 mm Hg. The initial rate and tidal volume were not ...